Many different types and shapes of samplers for molten metal have been developed or proposed in recent years. These include the samplers disclosed in my previous U.S. Pat. Nos. 3,457,790; 3,452,602; 3,686,949; and 4,046,016; and the foamed ceramic or castable silicate compositions described in my U.S. Pat. No. 3,561,494 provide excellent heat insulating coatings protecting samplers and lance tubes from the high temperature molten metal during the sampling operation, and assuring proper chilling of the melt samples.
A sampler for molten metal must provide a sampling chamber or cavity enclosed inside a hollow chill mold, which is provided with slots or vents capable of venting the air displaced by the inrushing molten metal. Surrounding insulating material, such as a foamed ceramic coating, preserves the chill mold at a temperature far below that of the molten metal for a period long enough to chill the inrushing molten sample to the consistency of slush. The sampler is then removed from the melt, and cooling is continued by exposure to the atmosphere at room temperature, or to a quenching bath of water or liquid nitrogen, for example.
The samplers of my previous patents produce reliable and homogeneous samples in the deep immersion sampling operations in which they are customarily used or in killed steel sampling operations requiring no deoxidizing treatment. When a high oxygen content must be counteracted, or a deoxidized sample must be taken from a shallower melt, as in a continuous caster operation, high reliability, approaching one hundred percent, can be achieved utilizing the features and combinations of features characterizing the samplers of the present invention. Entrained gas bubbles, forming inclusions or voids, are virtually eliminated by these samplers. Metallic deoxidants in strip, wire or powdered form are thoroughly dispersed just prior to the sampling operation, and the inflowing surge of molten metal entering the sampling chamber inside the chill mold is virtually unimpeded. The unique vent slots release the air displaced by the entering sample with unusual effectiveness. The high precision chill molds produce precisely dimensioned samples suitable for spectrophotometric analysis and other metallurigcal tests with nearly perfect reliability, in the precise dimensions desired with smooth surfaces and with homogeneous compositions, accurately representing the composition of the metal.
Accordingly, the principal object of the present invention is to provide a highly efficient molten metal sampler capable of producing homogeneous and representative samples taken from the central portion of a body of molten metal, chilled and solidified for metallurgical testing with a high degree of reproducibility and reliability.
Another object of the invention is to provide such molten metal samplers incorporating metal chill molds providing a plurality of rows of vent slots to release air displaced by inrushing molten metal.
A further object of the invention is to provide such molten metal samplers which are easily detached from the lance tube for examination, after the chilled sample is removed from the melt.
Another object of the invention is to provide such molten metal samplers in which the chill mold parts are formed by powder metallurgy techniques, achieving high precision with a minimum of machining operations.
Still another object of the invention is to provide such molten metal samplers in which deoxidant material is carried in a sealed ablative deoxidant chamber just outside the entrance portal of the sampler itself, with the sealed entrance cap of the deoxidant chamber being adapted to melt, following exposure to the high central temperatures of the body of molten metal, admitting the melt and releasing the displaced air in an upward direction with consequent turbulent mixing of the melt and deoxidant material carried in the chamber to produce thorough deoxidizing just prior to entrance of the molten metal into the sampler's chill mold, with the deoxidant chamber walls being designed to be melted and carried away, leaving its ceramic insulating coating forming part of the floating slag layer as the sampling operation is completed.
A further object of the invention is to provide such molten metal samplers capable of forming two samples simultaneously, both of which are filled by the deoxidized molten metal in the deoxidant chamber prior to its disappearance from the sampler.
Another object is to provide a variable or adjustable cooling rate by using preselected chilling discs of selected thickness, which allow sampling at predetermined higher or lower temperatures, reliably delaying the freezing of the sample until the sampler is filled.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the features of construction, combinations of elements and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.